kurvy

Every time I take my xj out, i hear this weird grinding noise coming from under the car. Usually when I set in at about 55 mph or so and I let off the throttle, the grinding noise will set in and if i push on the throttle, the noise will go away, i was wondering what could be causing this noise??

BuckB91XJ

A bad U-joint can cause that symptom. Is your XJ lifted and if so, how much, and if so, did you do anything about rear driveshaft vibes? Of course a worn rear differential can cause that also.

89cherokeelimited

My jeep is actually doing that right now and it's the rear gears in the differential. I'm gonna try to change mine out tuesday.

kurvy

my XJ has stock lift and i have not touched anything at the rear at all. what would exactly happen if i didn't get it replaced??

how much does a u joint cost??

do you think i need a whole new shaft or just the u joint itself?

LaredoBucket

My XJ seems to be doing the same. The noise seems to coming from tranny area. It's really loud when Im in 5th gear. I recently put a 3" lift on it and changed my drums and pads.

bishop letov

If it is your u joints or your rear and the noise is pretty loud on coasting( foot of the gas) then you could be asking to be stuck somewhere. If you do any type of backwoods or heavy wheeling it would be tough to get your rig back to pavement.

Had a 1992 chevy half ton 5 speed. Rear was making the baaaddd noise when I got the truck. I drove it like that for about 15k miles (traveled far for work) long story short. Rainy day and i let the clutch out too quick. tires slipped and grabbed again. Next thing I know I couldnt go about 10 miles per hour because the pinion would bind with the ring gear so bad it would just dam near send me through the windshield. I wound up driving it in reverse ( the only way it would move without binding) to my bosses house. I was two hours from home but about 5 miles from his house. Had to have someone come get me and lost my ride for 4 days.

Fix it on your schedule. Dont wait for it to fail and possibly leave you looking uncool in front of your friends or girl.

in the long run it could cost you more to repair it if you wait. Broken driveshaft from a really worn out u joint makes dents under the rig and scares the living crap out of you when it thumps against the floor a couple of times. even worse when you twist it so bad you have to replace it... Had to on my 77 k5 blazer and was limping home in 4wd.

u joint ... 20 bucks for the greasible type ( dont buy the cheaper non greasible) you wont have to replace the shaft unless its cracked, bent or dented really bad (weakens the shaft). reaplace both of the ujoint at the same time on the rear driveshaft this way you know its done.

boneyard rear... 20-200 really depends on the yard and if its a u pull it or full service boneyard.If your going to have it apart and havesome cash burning a hole in your wallet I would throw in a locker then so that you dont have to crack it back open later.

Rebuild your rear... could go anywhere from 400 to 700 out here in Pa. they replace the ring and pinion and properly build it.